A police officer who was lauded as a hero after his fatal shooting triggered an intense and costly manhunt in fact committed suicide, carefully staging his death because he was about to be exposed as a thief, authorities said Wednesday.

Fox Lake Police Lt. Charles Joseph Gliniewicz embezzled thousands of dollars from the Fox Lake Police Explorer program for seven years, and spent the money on such things as mortgage payments, travel expenses, gym memberships and adult websites, Lake County Major Crimes Task Force Commander George Filenko said.

"We have determined this staged suicide was the end result of extensive criminal acts that Gliniewicz had been committing in fact he was under increasing levels of personal stress from scrutiny of his management of the Fox Lake Police Explorer program," Filenko said.

The commander then endured blistering questions from skeptical journalists about his handling of the two-month investigation.

"We completely believed from day one that this was a homicide," Filenko said. "Gliniewicz committed the ultimate betrayal."

Just before he died, Gliniewicz radioed that he was chasing three suspicious men in a swampy area near Fox Lake, a suburb north of Chicago. Backup officers later found the Army veteran's body about 50 yards from his squad car. His handgun wasn't found for more than an hour, even though it was less than three feet from the body, Filenko said.

Gliniewicz's death on Sept. 1 set off a large manhunt, with hundreds of officers searching houses, cabins and even boats on area lakes. Helicopters with heat-sensing scanners and K-9 units scoured the area for days. Some 50 suburban Chicago police departments and sheriff's offices assisted, racking up more than $300,000 in overtime and other costs, according to an analysis that the Daily Herald newspaper published in early October.

More than 100 people submitted to DNA tests as investigators sought matches to evidence collected at the crime scene - genetic tests that Filenko said ultimately found nothing. Asked Wednesday whether that evidence will now be destroyed, Filenko said he didn't know.

More than 100 investigators stayed on the case for weeks, even as questions arose and investigators began to concede that they could not rule out suicide or an accident. One hint came when Rudd announced that Gliniewicz was killed by a "single devastating" shot to his chest, prompting an angry response from Filenko, who said releasing such details put "the entire case at risk."

But as the case progressed, investigators were uncovering incriminating emails that Gliniewicz had sent, suggesting he felt his thefts were about to be exposed by an audit of the Explorer program.

In a brief statement, Village Administrator Anne Marrin said the officer even threatened her personally after she began asking tough questions.

To the public, the case remained a homicide investigation, even after authorities announced in October that Gliniewicz, 52, had been shot with his own weapon.

Authorities released only the vague description of three suspects that Gliniewicz had radioed in - two white men and a black man. They tracked down three men captured on a home security video system, but all had rock solid alibis, Filenko said, and no one was ever arrested.

Gliniewicz was a 30-year police veteran and expert crime scene investigator, his boss said, and took elaborate steps to try to make it look like he died in a struggle, including shooting himself twice in the torso. The Lake County coroner, Dr. Thomas Rudd, said his head was bruised in ways that may have been intentional. He was struck by two rounds, one that hit his ballistic vest and another that pierced his upper chest.

Gliniewicz was he was held up on national television as a hero who died doing his job in a dangerous environment. An outpouring of grief swept Fox Lake, a village of 10,000 about 50 miles north of Chicago. The officer's picture was hung in storefront windows and flags flew at half-staff in his honor. Others described him as tough when needed, but also as sweet and a role model to youngsters aspiring to go into law enforcement.

Gliniewicz's family had dismissed the suggestion of suicide. The tattooed officer with a shaved head, who was married and had four children, "never once" thought of taking his own life, and was excited about his retirement plans, his son D.J. Gliniewicz said.